buildTransaction

Tron private extension. Constructs an unsigned Tron transaction; sign it and broadcast via HTTP /wallet/broadcasttransaction or /wallet/broadcasthex (JSON-RPC itself does not provide a broadcast endpoint).

• Source: framework/src/main/java/org/tron/core/services/jsonrpc/TronJsonRpcImpl.java#buildTransaction
• Ports: FullNode 8545 only (the Solidity port throws -32601)

Request parameters

Position	Type	Required	Description
params[0]	object	yes	BuildArguments (extends CallArguments; fields below)

BuildArguments fields (framework/src/main/java/org/tron/core/services/jsonrpc/types/BuildArguments.java):

Field	Default	Description
from	required	Sender address (hex or base58check)
to	depends	Target address; empty for contract deployment
gas	0x0	Maximum energy consumed by the transaction; ultimately feeLimit = gas × eth_gasPrice (sun)
value	null	TRX amount (sun, hex)
data	null	Contract bytecode (deployment) or calldata (trigger)
tokenId	0	TRC10 token id (used for TransferAssetContract)
tokenValue	0	TRC10 amount
abi	""	ABI JSON string for contract deployment (e.g. [{...}])
name	""	Contract name when deploying
consumeUserResourcePercent	0	User-shared resource percentage (0–100)
originEnergyLimit	0	Deployer's max energy per call
permissionId	0	Multi-sig permission id
extraData	""	Memo data written into the transaction
visible	false	Whether output addresses / strings use base58 / UTF-8

Contract type inference (BuildArguments.getContractType):

Condition	ContractType
to empty + data non-empty	CreateSmartContract
to is a contract address	TriggerSmartContract
to is a regular account + tokenId>0 + tokenValue>0 + value empty	TransferAssetContract
to is a regular account + value non-empty	TransferContract
Otherwise	throws -32600 invalid json request

# Example: build a TRX transfer (1 TRX = 1e6 sun)
curl -X POST https://nile.trongrid.io/jsonrpc \
  -H 'Content-Type: application/json' \
  -d '{
    "jsonrpc":"2.0","id":1,"method":"buildTransaction",
    "params":[{
      "from":"0x41a614f803b6fd780986a42c78ec9c7f77e6ded13c",
      "to":"0x4112ab345eafdc9af9eaad7c97a2e9c3d4ddc0d7e1",
      "value":"0xf4240"
    }]
  }'

Response

{"transaction": {...}} — directly maps to Tron protocol.Transaction (the hex field encoding matches the format returned by HTTP /wallet/createtransaction). The example below is the real response captured from the Nile testnet curl above:

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "transaction": {
      "visible": false,
      "txID": "231371e531760758ea3a74dd4bce4934ad6d4cc71dfae1907f072c39de4c0c2f",
      "raw_data": {
        "contract": [
          {
            "parameter": {
              "value": {
                "amount": 1000000,
                "owner_address": "41a614f803b6fd780986a42c78ec9c7f77e6ded13c",
                "to_address": "4112ab345eafdc9af9eaad7c97a2e9c3d4ddc0d7e1"
              },
              "type_url": "type.googleapis.com/protocol.TransferContract"
            },
            "type": "TransferContract"
          }
        ],
        "ref_block_bytes": "1d00",
        "ref_block_hash": "081a3fe1f1440f1d",
        "expiration": 1777438164000,
        "timestamp": 1777438106738
      },
      "raw_data_hex": "0a021d002208081a3fe1f1440f1d40a088c8bcdd335a67080112630a2d747970652e676f6f676c65617069732e636f6d2f70726f746f636f6c2e5472616e73666572436f6e747261637412320a1541a614f803b6fd780986a42c78ec9c7f77e6ded13c12154112ab345eafdc9af9eaad7c97a2e9c3d4ddc0d7e118c0843d70f2c8c4bcdd33"
    }
  }
}

ref_block_bytes / ref_block_hash come from the latest block at construction time; expiration = timestamp + 60s; txID is the SHA256 hash of raw_data, so it changes whenever the above fields change — two calls of the same request will produce different txID values.

feeLimit = gas × wallet.getEnergyFee(), automatically written to raw_data.fee_limit only for CreateSmartContract / TriggerSmartContract; TransferContract / TransferAssetContract don't need feeLimit (this is why the raw_data above has no fee_limit field).

Error responses

Trigger	Code	message
The current node is not a FullNode (Solidity)	-32601	the method buildTransaction does not exist/is not available in SOLIDITY
from missing / invalid	-32600	invalid json request
Contract type inference fails (e.g. to + data + value all empty)	-32600	invalid json request
to non-empty but invalid hex / wrong length	-32602	passes through addressCompatibleToByteArray message
value is not valid hex	-32602	invalid param value: invalid hex number
gas is not valid hex	-32602	invalid param value: invalid hex number
tokenId invalid after string conversion (TRC10 path only)	-32602	invalid param value: invalid tokenId
Contract validation fails (ContractValidateException)	-32600	passes through message
Internal exception	-32000	passes through message

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